Bluetooth Low Energy is becoming more and more popular for sensor applications. It not only needs much less energy than normal Bluetooth interfaces, even the transmission rage is longer. It isn’t design for huge data transfers, but that’s often not needed.
Unfortunately almost none of the popular development platforms (Arduino, ESP8266) comes with BLE onboard. This isn’t a big problem as there are many BLE modules available.
However, make sure you read the documentation of the module before ordering it.
I just received this small and inexpensive HM13 module. I wanted to use it to read data from a BLE plant sensor. Unfortunately when I checked the documentation I noticed that the firmware on this board is designed for serial data transmissions over BLE. It seems you can’t use it as a general purpose BLE interface.
Therefore check the documentation of a module before ordering to make sure the module supports the features you need.